<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
<style>
*{
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}    
body{
    background-color: black;
}
ul,
ol {
  list-style: none;
}
ul{
    display: flex;
    gap: 10px;
}
li{
    height: 20px;
    width: 20px;
    border-radius: 50%;
    background-color: antiquewhite;
}
li:hover{
    /* 阴影不占位置不影响其他 */
    box-shadow: 0 0 0 4px rgba(255, 255,255 , 0.5);
}

</style>
</head>
<body>
    
    <ul>
        <li></li>
        <li></li>
        <li></li>
    </ul>
</body>
</html>